Trench digger blade



p 24', .3 w. E. GEORGE ETAL TRENCH DIGGER BLADE Filed Nov. 1'7, 1960 ATTY$ United States Patent O 3,104,481 TRENCH BIGGER BLADE Warren E. George, Auburn, and Glenn W. Mclninch, Omaha, Nebiz, assignors to Auburn Machine Works, Inc., Omaha, Nehru, acorporation of Nebraska Filed Nov. 17, 1960, er. No. 70,028 3 Claims. (1. 37-191) The present invention relates generally to digger blades for use with trenching apparatus of the type employing an endless driven sprocket chain and, more particularly, to an improved digger blade mounting arrangement.

It is a general object of the present invention toprovide an improved digger blade construction adapted to be mounted on an endless driven chain of the type employed in trenching apparatus. A related object of the invention is to provide a novel digger blade mounting-arrangement characterized by a high degree of lateral stability and freedom from wobble even in the face of hard usage.

It is another object of this invention to provide an improved mounting arrangement for trencher digger blades having a minimum number of components and characterized by a greatly increased useful life. In this connection, it is an object of the invention to provide a digger blade in which wear at the point of mounting is substantially reduced.

It is a further object of this invention to provide a digger blade mounting arrangement wherein the retaining pins used to hold the pivot pins in position are protected from stones and other obstructions so as to minimize the danger of throwing the chain and thus avoiding a possible hazard to both the apparatus and the operator. It is a further object of the invention to provide a digger blade mounting arrangement wherein the walls of the mounting holes which engage the pivot pins are hardened incident to the :cold forming operations which are performed, thus decreasing any tendency for the holes to wear or enlarge in use.

These and other objects and advantages of the invention are attained by the construction and arrangement shown as an exemplary embodiment in the accompanying drawing, in which:

FIGURE 1 is a plan view of a portion of a digger chain on which are mounted a plurality of digger blades embodying the present invention;

FIG. 2 is a transverse section taken substantially along the line 2-2 of FIG. 1;

FIG. 3 is a side elevation of a digger blade embodying the present invention;

FIG. 3a is a side elevation taken from the opposite side of the digger chain and illustrating one of the chain links;

FIG. 4 is a fragmentary diagrammatic view showing the initial punching of the holes in a blade;

FIG. 5 is a fragmentary diagrammatic view showing the subsequent piercing operation; and,

FIG. 6 is a fragmentary sectional view taken substantially along the line 6-6 of FIG. 3 showing the means for securing the digger blade and pivot pin together.

While the invention has been illustrated and will be described in connection with a preferred embodiment, it will be understood that the invention is not limited to this specific embodiment, and it is intended to cover such equivalent and alternative constructions as may fall within the spirit and scope of the appended claims.

Referring more specifically to the drawing, there has been illustrated in FIG. 1 a portion of an endless driven sprocket chain 10 which is adapted to support a plurality of trench digger blades and which is lowered into the ground on a suitable boom. For a detailed description of a typical mechanism for lowering and driving the sprocket chain 10, reference is made to the prior Schmidt Patent 3,104,481 Patented Sept. 24, 1963 No. 2,519,076, owned by the assignee of the present invention.

In the present arrangement the digger blades are provided in pairs, one on the right hand side'ofthe chain and the other on the left hand side, with the pairs having a different width or span. The first pair of blades, indicatcd at 1'1, 12 define a cutting width substantially equal to the width of the chain (FIG. 2). The second pair of blades, indicated at 13, 14 define a greater cutting width,

extending laterally away from the center line of the chain before curving back towards the chain.-

Each blade in the series has a sharpened leading edge and a flat base portion for mounting on the side of the chain. Taking the blade 14 by way of example (FIGS. 2 and 3), it includes a curved portion 15 having a cutting edge 16 anda fiat base portion 17. To provide support at the trailing edge 18 of the blade and to resist ground reaction, the blade includes a heel 19 which engages the successive link 26 of the chain. It will be understood that as the chain is urged forwardly the successive pairs of blades cut through the ground with a broaching'action and lift the loosened earth to the surface for disposal by conventional apparatus.

In accordance with the present invention each of the digger blades is formed of a relatively thin metal plate having a flat base portion secured to the chain by pivot pins and embossed so that the pin receiving surfaces have a length in the axial direction which substantially exceeds the thickness of the metal. In the present embodiment the blade 14 is secured in seated position on'the chain by pivot pins 21, 22, engaging apertures 23, 24, respectively, formed in the base portion 17 of the blade (FIGS. 2 and 3). On the opposite side of the chain, a link 25 is pro-' vided having registering apertures 27, 28 (FIG. 3a). The outer surface of the blade base portion 17 is provided with integral embossments 31, 32 respectively, thus increasing the eifective axial length of the pin openings 23, 24. The link 25 preferably is formed with similar embossments33, 34.

Embraced by the blade 14 and the opposed link 25 are two inner links 35, 3 6- and a roller 37, all of which are snugly telescoped over the pin 21.

In accordance with one of the aspects of the invention,

a transverse retaining pin is provided atthe blade end ofthe pivot pin 21, in registration with a groove formed in the boss 31 so that the retaining pin is protected against the abrading action of the dirt during the trenching operation while maintaining the pivot pin locked with respect to the blade. Thus, a retaining pin 38 is provided at the right hand end of the pin 21 as viewed in FIG. 2, with the ends of the pin being received in a groove 39 formed in the boss. In the preferred embodiment a similar retaining pin 40 is used at the opposite end of the pivot pin and engaging a groove 41 in the boss 33. The second pivot pin 22 is provided with correspondingly numbered retaining pins. While the retaining pins may take a number of different forms, I prefer to use pins of the split tubular type, formed of spring steel and frictionally retained in the holes formed in the ends of the pivot pins. Retaining pins of this type are available to the trade under the name of roll pins since they are conventionally formed by a rolling process. -The pins are preferably chosen to have a snug frictional fit, permitting intentional insertion and removal with only limited force. It will be understood however, that because of the protection provided by the grooved embossment, there'is no likelihoodof unintentional loss of'a pin in use. Moreover, there is no possibility that the pins will become crooked or broken due to impact with rocks orthe like. Since the projecting ends of each retaining pinare received within an associated key-way 1 critical to the present invention.

increasing the lateral stability of the blade and reducing the possibility of the blade wabbling with respect to the chain. Such a mounting arrangement allows the digger blade to be made of plate metal stock of limited thick- .ness, resulting in less material cost and, in addition,

reducing-the weight which must be carried by the chain. Digging performance is improved.

In keeping with the present invention, a procedure is employed for simply and expeditiously forming each raised boss while simultaneously increasing the wearing ability of the aperture or bore formed therein. To this end, the planar base portion 17 of the digger blade is,

positioned on a die block 44 (FIG. 4) having a suitable punch receiving opening 45 formed therein. A punch 46 is then driven through the base portion 17 and into the waiting opening in the die block to form an initial aperture 48 of a diameter substantially less than that of the pin 21 which is to be accommodated. Merely'by way of example, if the finished elongated bore 28- is to have a diameter of three-eighths of an inch for snuglyreceiving a pivot pin 21 of comparable diameter, it is desirable during this first :forming step to utilize a punch 46 on' the order of one-quarter inch in diameter. Of course, it will be appreciated that the particular type of punching apparatus used for driving the punch 46 is not Moreover, when it is desired to simultaneously form two mounting apertures in each digger blade, it will be understood that the punching apparatus may include a pair of appropriately spaced punches and a suitable die block. It will also be apparent to those skilled in the art that the initial apertures 48 could be formed by drilling if so desired.

Following formation of the initial aperture 48 in the base portion 17, a piercing tool and die are used to enlarge the opening to the diameter of the pivot pin. Thus, the blade is positioned on a second die block 49 (FIG. having an enlarged die opening 50 formed therein alined with a piercing tool 51 of a diameter corresponding to the pin to be received and having a tip 52. of reduced cross section. Since the shank portion of the piercing tool 51 is of greater diameter than that of the punch 46, a swaging action occurs as the-piercing tool is driven through the aperture 48, thus causing the surrounding metal to flow into the die block opening and forming the integral upraised boss "31 previously referred to.

It will be appreciated by those skilled in the art that numerous advantages result from this type of forming operation. Not only is the mounting bore 23 formed in the base portion 17 of the blade of substantial length, thus greatly increasing lateral blade stability, but additionally, the piercing tool 51 coins the surface of the bore to form a smoother and more wear resistant surface. Since the surface of the elongated bore is much smoother than could otherwise be obtained by driving a punch through a blade of conventional thickness, the diameter of the hole is more closely controlled, thereby insuring a snug fit with the pivot pin 21. g

The same procedure may be used to form the apertures 27, 28 in the opposed link 2-5.

When it is desired to prevent relative rotation between the pivot pin 21 and the digger blade, the key-way groove 39 may be. formed in the upraised boss 31 as a third step in the formation of the present blade mounting. It will be understood that the groove may be formed in various ways, for example, by a slot miller.

Using the construction and fabrication procedure set forth above, a digger blade is produced which amply meets the objects of the invention, being lower in cost and capable of more satisfactory performance than conventional blades.

We claim as our invention:

1. For use in trenching apparatus of the type employing an endless driven sprocket chain including a plurality of transversely extending pivot pins and locking means extending radially through the pivot pins, an article of manufacture comprising, a digger blade formed of a,

plate of metal of limited thickness having a cutting por! tion and an integral, substantially planar base portion,

saidbase portion providing a mounting surface having a plurality of apertures extending therethrough for mount- ,ing said blade on the pivot pins, and a plurality of laterally extending raised bosses formed on one side of said base portion, each boss substantially surrounding one of said apertures so that the wall of each aperture defines an elongated *bore substantially exceeding the thickness of the plate of metal of which the digger blade is formed,

each of said bosses having a radially disposed key-way formed therein adapted to receive the locking means as-:

sociated with the corresponding pivot pin.

. 2. For use in trenching apparatus of the type employing an endless driven sprocket chain adapted to be lowered into the earth, the combination comprising, a digger blade formed of a plate of metal of limited thickness having a cutting portion and an integral, substantially planar base portion, said base portion providing a mounting surface having a plurality of apertures extending therethrough for mounting said blade on the side ofsaid. chain, a plurality of laterally extending raised bosses.

formed on one side of said base portion, each boss substantially surrounding tone of said apertures and defining therewith an elongated bore, a pivot pin extending transversely through said chain and said elongated bore, and a retaining pin extending radially through said boss an'd said pivot pin. 1

3. For use in trenching apparatus of the type employ- 7 ing an endless driven sprocket chain adapted to be' lowered into the earth, the combination comprising, a digger rblade formed of a plate of metal of limited thickness having a cutting portion and an integral, substantially planar :base portion, said base portion providing a mount.-

ing surface having a plurality of apertures extending therethrough for mounting said blade on the side of said chain, aplurality of laterally extending raised bosses formed on one side of said base portion, each boss substantially surrounding one of said apertures and defining I therewith an elongated bore, a transverse groove formed in each raised boss, a pivot pin extending transversely through. said chain and said elongated 'bore, and a retainingpin disposed in said groove and extending radially through said pivot pin. 4

T References titted in the file of this patent UNITED STATES PATENTS Hughes Jan. 4,1915

Zahodiakin; May 1, 1956 

1. FOR USE IN TRENCHING APPARATUS OF THE TYPE EMPLOYING AN ENDLESS DRIVEN SPROCKET CHAIN INCLUDING A PLURALITY OF TRANSVERSELY EXTENDING PIVOT PINS AND LOCKING MEANS EXTENDING RADIALLY THROUGH THE PIVOT PINS, AN ARTICLE OF MANUFACTURE COMPRISING, A DIGGER BLADE FORMED OF A PLATE OF METAL OF LIMITED THICKNESS HAVING A CUTTING PORTION AND AN INTEGRAL, SUBSTANTIALLY PLANAR BASE PORTION, SAID BASE PORTION PROVIDING A MOUNTING SURFACE HAVING A PLURALITY OF APERTURES EXTENDING THERETHROUGH FOR MOUNTING SAID BLADE ON THE PIVOT PINS, AND A PLURALITY OF LATERALLY EXTENDING RAISED BOSSES FORMED ON ONE SIDE OF SAID BASE PORTION, EACH BOSS SUBSTANTIALLY SURROUNDING ONE OF SAID APERTURES SO THAT THE WALL OF EACH APERTURE DEFINES AN ELONGATED BORE SUBSTANTIALLY EXCEEDING THE THICKNESS OF THE PLATE OF METAL OF WHICH THE DIGGER BLADE IS FORMED, EACH OF SAID BOSSES HAVING A RADIALLY DISPOSED KEY-WAY FORMED THEREIN ADAPTED TO RECEIVE THE LOCKING MEANS ASSOCIATED WITH THE CORRESPONDING PIVOT PIN. 